2D Barcode
Linear Barcode
MSI Plessey
MSI Plessey
MSI plessey barcode symbology is also known as Plessey and Modified Plessey barcode symbology. MSI Plessey barcode symbology is a numeric-only, continuous, non-self-checking symbology with variable length. MSI was designed by the MSI Data Corporation in 1970s. It was originally invented to be used primarily to use in libraries, but now it is mainly used to mark retail shelves for inventory controlling system.
Encoding Data of MSI Plessey Barcode Symbology
MSI plessey barcode symbology is numeric-only barcode, invalid character setting ranges from 0 to 9.
Structure of MSI Plessey Barcode Symbology
MSI plessey barcode symbology is composed of the parts below:
• A leading start character which is composed of a wide bar and a narrow space
• Character digit encoded in the message
• The checksum digit calculated automatically by the software to prevent scanning error
• The trailing stop character which is composed of a narrow bar, wide space and a narrow bar
How to Encode MSI Plessey Barcode Symbology
The MSI Plessey Barcode Symbology is expressed by a binary number of black bar (1) and white bar (0).

ASCII CHARACTER 0 mapped as 100100100100
ASCII CHARACTER 1 mapped as 100100100110
ASCII CHARACTER 2 mapped as 100100110100
ASCII CHARACTER 3 mapped as 100100110110
ASCII CHARACTER 4 mapped as 100110100100
ASCII CHARACTER 5 mapped as 100110100110
ASCII CHARACTER 6 mapped as 100110110100
ASCII CHARACTER 7 mapped as 100110110110
ASCII CHARACTER 8 mapped as 110100100100
ASCII CHARACTER 9 mapped as 110100100110
Checksum calculation of MSI Plessey Barcode Symbology
The check digit of MSI plessey barcode symbology could be 1 or 2. Calculation method differs when different software is used. The most commonly used computing method of MSI plessey barcode symbology is Modulo 10, 2 Modulo 10 and Modulo 11.

### Module 10 method calculation steps

1. The new number creation is based on the original barcode. Thus the digit in the last right position of the new code is the digit in the last right position of the old number.
2. Multiple the new numbers with 2
3. Take the result of step 2 and assigned it in the last right position of the barcode. Add the result of the step 2 and other digits not used in the used to create the new number.
4. Employ the modulo 10 calculation method to do with the result summed in step 3. Add one number to let the result to be even divided by 10. The number added is the checksum digit.

### 2 Modulo 10 method calculation steps

2 Modulo 10 means the checksum digit of MSI plessey barcode symbology has 2 check digits. The second checksum digit is appended immediately after the first checksum digit. The calculation method is the same with Modulo 10 method. Just also take the first check digit to be calculated as new barcode in the second checksum digit computing.

### Module 11 method calculation steps

The third method to calculate the check digit of MSI plessey barcode symbology is Module 11. Details please refer to the steps below:
1. Find the right most digit of the barcode; assign the weight value 2 to it.
2. The next right most digit is assigned with weight value of 3. Increasing each position with relevantly weight value by 1 from right to left until you reach 7. Then goes back from 2 to 7 again.
3. Multiple the digit value with its relative weight value
4. Sum up all the result. Add one number on it which helps the summary to be evenly divided by 11. The number added on it is the check digit of barcode MSI Plessey.